# Kubernetes auto scaling
整體在Hyper-v 上實作，可以把我們之前的 service 部屬到 container pod 管理很多 service 可以配合 k8s 去進行集群的控管，因為負載不同也可以自行擴容等等，可能後續會再加入 aws 進行其他研究，
基本上跟以前hadoop 差不多灌完環境在複製一份虛擬機就好

master
node

個別下指令
#hostname 方便區別

# sudo hostnamectl set-hostname <name>
# hostname



# 設定docker開機自動啟動，跟查看啟動狀

# sudo systemctl enable docker
# sudo systemctl start docker
# sudo systemctl status docker

# 強制關閉 swap
這樣可以kubelet重新開機服務不會開不起來

# sudo swapoff -a
註解掉有swap 
vim /etc/fstab 

# kubeadm、kubelet 和 kubectl 安裝

sudo apt-get update && sudo apt-get install -y apt-transport-https curl

curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | sudo apt-key add -

cat <<EOF | sudo tee /etc/apt/sources.list.d/kubernetes.list
deb https://apt.kubernetes.io/ kubernetes-xenial main
EOF

sudo apt-get update

sudo apt-get install -y kubelet kubeadm kubectl

# Master 端執行

export KUBECONFIG=/etc/kubernetes/admin.conf
sudo systemctl daemon-reload
sudo systemctl restart kubelet

# sudo kubeadm init --pod-network-cidr=10.244.0.0/16 --service-cidr=10.245.0.0/16 --
apiserver-advertise-address=<master_IP>


# mkdir -p $HOME/.kube
# sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
# sudo chown $(id -u):$(id -g) $HOME/.kube/config

$ mkdir -p $HOME/.kube
$ sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
$ sudo chown $(id -u):$(id -g) $HOME/.kube/config

# Kubeadm - flannel
讓所有pod都可以加入到區域網

 sudo kubectl apply -f 
https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml

# node 端執行
加入節點到master
master 檢查節點

# Master 端執行

 sudo kubectl apply -f https://k8s.io/examples/application/deployment.yaml

注意這兩個label

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
spec:
  selector:
    matchLabels:
      app: nginx <=== 注意要與service 匹配
  replicas: 2 # tells deployment to run 2 pods matching the template
  template:
    metadata:
      labels:
        app: nginx <=== 注意要與service 匹配
    spec:
      containers:
      - name: nginx
        image: nginx:1.14.2
        ports:
        - containerPort: 80

 sudo kubectl get pod,deploy


# 觀察指令

sudo kubectl describe pod <pod_ID>
sudo kubectl describe service_ID <service_ID>
sudo kubectl describe hpa_ID <hpa_ID>
sudo kubectl describe deploy <deploy_ID>

# service

 wget 
https://raw.githubusercontent.com/kubernetes/website/master/content/zh/examples/service/netw
orking/nginx-svc.yaml

apiVersion: v1
kind: Service
metadata:
  name: my-nginx
  labels:
    app: nginx  <===注意要與service 匹配
spec:
  ports:
  - port: 80
    protocol: TCP
  selector:
    app: nginx  <===注意要與service 匹配

執行

# Kubernetes auto scaling
官方文檔案
https://kubernetes.io/docs/tasks/run-application/horizontal-pod-autoscale-walkthrough/

## install Metrics Server
Metric-Server 是 in memory 的 monitor，他不會將監控的資料儲存到Disk或
掛載的Volume，所以無法獲得過去的監控資料。

# wget https://github.com/kubernetes-sigs/metrics-server/releases/latest/download/components.yaml

下載並修改yaml 檔案

- --kubelet-preferred-address-types=InternalIP
- --kubelet-insecure-tls

這邊是當你的 HPA auto scaling run 起來的要抓取 pod 裡面的硬體資訊 memory or packet or cpu 使用率等等
沒有的話k8s hpa target 會呈現unknown
# nginx-hpa.yaml

apiVersion: autoscaling/v1
kind: HorizontalPodAutoscaler
metadata:
  name: helloworld-hpa
  namespace: default
spec:
  scaleTargetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: nginx-deployment
  minReplicas: 2
  maxReplicas: 7
  targetCPUUtilizationPercentage: 20

 sudo kubectl create –f nginx-hpa.yaml


# 增加負載
類似壓力測試

kubectl run -i --tty load-generator --rm --image=busybox --restart=Never -- /bin/sh -c "while sleep 0.01; do wget -q -O- http://php-apache; done"

# 負載增加 pod 狀況
# 負載減少 pod 狀況
過幾分鐘才會平衡

kubeadm join 172.22.219.214:6443 --token tv1in7.ts67215bd2n3ovci \
--discovery-token-ca-cert-hash sha256:c9df78252d6080855853d5bde5f73ea4e89bc0619a72b33cc73072efbc8b4e2c

sudo kubeadm join 172.30.124.19:6443 --token 1wquun.s2xs7qu72riy05sb \
--discovery-token-ca-cert-hash sha256:cd3167bc76d52aef14a26a034979648d79150cd3a2f1b4e0ed1c9d79b0887753